Add Python 3.10 to CI (adap#1320)

.github/workflows/flower.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        python: [3.7.12, 3.8.12, 3.9.10]
+        python: [3.7.12, 3.8.12, 3.9.10, 3.10.5]
     steps:
       - uses: actions/checkout@v2
       - name: Set up Python